This invention relates to optical communication systems and, more particularly, to a system arrangement for mounting modular optical network units.
Dense Wavelength Division Multiplex (DWDM) optical transmission systems have been typically is employed to increase the capacity of optical fibers as the traffic load on the system increases. Usually, these systems tend to be high capacity, high bit-rate per channel systems such as long haul telephony. Presently many fiber facilities are at or near exhaustion due to increasing traffic, much of which has been generated by new services, but the application of DWDM technology to these systems will increase the fiber capacity many times over.
Another DWDM application, in what tends to be of shorter length and have much lower bit-rate per channel applications, is in local optical networking. In this application, the systems evolve from a low first cost (and capacity) and have low incremental cost as the traffic capacity grows or changes. Examples of such systems include local cable television distribution systems and collegiate or corporate campus data networks. In these systems, a cable TV company providing Internet access to customers would add channels, for example, as different neighborhoods start to receive service. Also, at a point in the future, the provider would have to increase the transmission capacity to a given neighborhood as the popularity of the service grew. Such typically non-telephony type networks as these require small, compact size terminals, ease of use, and low cost.
In many of the above applications, the space for housing such equipment is limited and existing shelf hardware designs (including all mounting hardware, card guides, and backplanes) can not be easily and economically made to physically accommodate modular capacity growth. As a result, changes in capacity often resulted in expensive shelf redesigns, rearrangements, and unfortunately, in some cases, even service interruptions.
The optical communication apparatus of the present invention is directed to solving the prior art problems using a Modular Carrier (MC) unit which shares power and control among a plurality of Optical Network Units (ONU) which are plugged into it, thereby increasing the ONU density in an existing equipment shelf. In one embodiment, the MC unit together with its four ONU units is arranged to slide into an existing card slot of the existing equipment shelf and occupy the space of the adjacent slot. The result is a doubling of the capacity over the conventional technique of using a separate slot for each ONU unit.
More particularly, our optical apparatus comprises a common Module Carrier (MC) unit including a power unit, a board controller, and an equipment detector unit for detecting an electrical ONU present signal indicative of the connection of an ONU, the board controller being responsive to the ONU present signal for (1) signaling the power unit to apply power to the connected ONU and (2) for sending control signals to connected ONU. An interface unit includes a connectorized backplane card connected to receive power and control signals from the MC unit, couples a plurality of ONU present signals to the MC unit, and is arranged for mounting each of the plurality of ONU in a separate connector slot of the connectorized backplane card. One or more ONUs may be plugged into the interface unit, each ONU is adapted for mounting into a separate connector slot to connect to the backplane card and arranged to receive the power and control signals from the MC unit, is adapted to generate the ONU present signal, and is adapted to couple optical signals into and out of the ONU. In accordance with the present invention, the ONU may be an Optical Translator Module(OTPM), optical regenerator, optical multiplexer, optical demultiplexer, optical monitor, etc.
According to another aspect of the invention, an ONU unit is adapted to mount into a separate connector slot of a MC unit and comprises circuitry for providing an ONU present signals indicative of the mounting of the ONU in a connector slot of the MC unit, circuitry for receiving power and control signals from the MC unit, and a power filter for controlling the rate at which power is applied to the ONU.